The present invention relates to the field of curb forming, and more particularly, to machines and methods for extruding and forming continuous curbs or borders.
Many commercial and residential property owners use some type of border or edging to enhance the appearance of their landscaping. For example, edging is used to separate or provide a transition from a flowerbed to a grass area. The edging also typically provides a root barrier. Conventional edging may include the use of wood, plastic, brick, pre-cast cement sections, chemicals or shoveling and trimming, for example.
Another type of edging is continuous custom concrete edging. The continuous concrete edging is formed using a portable curb forming and extruding machine such as those manufactured by The Concrete Edge of Orlando, Fla. Such machines typically include a reciprocating ram or an auger to force concrete or other building materials through a mold. The machine may also include a hopper for receiving the concrete material, and a motor and gear box for driving the ram or auger.
The continuous concrete edging may be about six inches high by about six inches wide, for example, and may be applied on parking lots, driveways, walkways, paths and around flowerbeds and other planting areas. Furthermore, the continuous concrete edging provides a permanent and durable root barrier that will not rot, separate or lose its luster even when run over by mowers and trimmers. Of course, the continuous concrete edging saves time on weeding and trimming and adds value to the property.
An example of an auger type machine is disclosed in U.S. Pat. No. 5,354,189 to McKinnon entitled xe2x80x9cCurb Forming and Extruding Apparatus.xe2x80x9d This curb extrusion device has a segmented vibrating hopper into which building materials are placed to fall onto two tapered counter rotating vibrating augers.
An example of a reciprocating ram type machine is disclosed in U.S. Pat. No. 5,527,129 to McKinnon entitled xe2x80x9cElliptical orbit compaction curb forming and extruding apparatus.xe2x80x9d This extruder has a reciprocating compacting member which on the compaction stroke simultaneously moves forward to compact the concrete and lifts upward slightly, between xc2xd and ⅝ of an inch, just before the return stroke to force the compressed concrete against the upper surface of the slip form.
One problem with these machines is referred to as concrete bridging. The concrete material being shoveled into the hopper is usually relatively dry so that it holds the form of the curb after being extruded from the machine. Unfortunately, this sometimes causes it to bridge from side to side in the hopper and not fall through into the chamber where the ram or auger is located to force the material through the mold. Because these machines are self-propelled via the curb being extruded through the mold, when bridging occurs, the machine stops and the operator has to manually break the concrete bridge with a shovel, for example. This results in wasted time and less efficient installation of the curb.
Another problem with a typical linear reciprocating ram type machine is the creation of voids, flat spots or weak areas in the extruded curb. The reciprocating ram moves in a linear motion from the back of the lower part of the hopper towards the mold or slip form. When the ram pulls back from the mold, the end of the exposed packed concrete is smoothed from the face of the ram. During the next cycle, more concrete is packed against the smoothed end of the concrete in the mold. As those skilled in the art are aware, such smoothed sections result in voids, flat spots or weak areas in the extruded curb.
In view of the foregoing background, it is therefore an object of the invention to provide a curb forming and extruding machine which forms continuous concrete edging while reducing voids, flat spots or weak areas in the extruded curb, and the problems caused by concrete bridging in the hopper.
This and other objects, features and advantages in accordance with the present invention are provided by a curb forming machine including a hopper carried by a frame and including an upper hopper section, for receiving curb forming material, and a lower hopper section. A curb extrusion mold is adjacent the lower hopper section for receiving the curb forming material therefrom to extrude a curb. Furthermore, a plunger and associated drive move the plunger along a path of travel including a forward position to force the curb forming material from the lower hopper section into and through the curb extrusion mold, an upward position so that the plunger extends into the upper hopper section, and a rearward position away from the curb mold and in the lower hopper section.
The path of travel of the plunger to the upward position is preferably greater than the path of travel between the rearward and forward positions. Moreover, the path of travel of the plunger to the upward position is about seven inches, and the path of travel between the rearward and forward positions is about four inches. The drive may include a motor and a gear box having an output shaft connecting the motor to the plunger. The drive may further include an eccentric arm rotatably connecting the plunger to the output shaft, a first shaft mounted to the frame, a second shaft connected to a medial portion of the plunger, and a plurality of rocker arms pivotally connecting the second shaft to the first shaft. A plurality of wheels may be connected to the frame with an associated steering mechanism for steering the curb forming machine.
Objects, features and advantages in accordance with the present invention are provided by a method of forming a curb including providing curb forming material into a hopper having an upper hopper section for receiving the curb forming material, and a lower hopper section, and providing a curb extrusion mold adjacent the lower hopper section for receiving the curb forming material from the lower hopper section and extruding a curb. The method also includes moving a plunger along a path of travel including a forward position to force the curb forming material from the lower hopper section into and through the curb extrusion mold, an upward position so that the plunger extends into the upper hopper section, and a rearward position away from the curb mold and in the lower hopper section.
A curb forming and extruding machine and method are provided to form continuous concrete edging while reducing and/or substantially eliminating voids, flat spots or weak areas in the extruded curb. The machine and method also reduce the problems caused by concrete bridging in the hopper. The motion of the plunger to extend into the upper section of the hopper eliminates concrete bridging and also scores the concrete as it packs it into the mold.